1. Field of the Invention
The present invention relates to optical collimators, and more particularly to an optical collimator having an integrated molding lens therein.
2. Description of the Prior Art
As optical fiber technology is being more broadly applied in the telecommunications, data communications and community antenna television (CATV) industries, the fiber optic component industry is now confronted with increasingly demanding requirements for good performance and high reliability. Currently, most design and manufacturing of in-line fiber optic components are based on optical collimators, which provide low-loss light transmission from the input fiber to the output fiber through an optical element. Optical collimators are basic building blocks of fiber optic components. The reliability and level of performance of fiber optic components depends heavily on the reliability and performance characteristics of their optical collimators.
A Graded Index (GRIN) lens is a popular optical element which is utilized in an optical collimator for collimating scattered light. As show in FIG. 1, a conventional optical collimator comprises an input optical fiber 1, an output optical fiber 2, a ferrule 3, a GRIN lens 4, a filter 5, an inner tube 6 and an outer tube 7. A through hole (not labeled) defined in the ferrule 3 receives the optical fibers 1, 2. The ferrule 3 and the GRIN lens 4 are aligned and fixed in the inner tube 6 with epoxy resin. The filter 5 is adhered to an end surface of the GRIN lens 4 with epoxy resin.
The conventional optical collimator has some disadvantages. First, the filter 5 is directly adhered onto the surface of the GRIN lens 4 with epoxy resin. During heating of the resin, the filter 5 is subjected to uneven heating. This changes and adversely affects performance of the filter 5. In addition, humidity created by the epoxy adversely affects performance of the optical collimator. Second, accurate alignment as between the ferrule 3 and the GRIN lens 4 depends on accurate formation of the inner tube 6. Therefore, the inner tube 6 must be made with unduly high precision. Third, the GRIN lens 4 is conventionally made by the ion exchange method. Therefore, the GRIN lens 4 must be further polished after initial formation. Furthermore, chemicals used in the ion exchange method are harmful to users and pollute the environment.
Therefore, an improved optical collimator that overcomes the above-described numerous disadvantages of the conventional optical collimator is desired.
Accordingly, an object of the present invention is to provide an inexpensive optical collimator having good optical performance.
Another object of the present invention is to provide an optical collimator that allows easy and precise fixing of its optical components.
A further object of the present invention is to provide an optical collimator that is environmentally friendly.
To achieve the above-mentioned objects, an optical collimator in accordance with a preferred embodiment of the present invention comprises an input optical fiber and an output optical fiber, a ferrule receiving the input optical fiber and the output optical fiber therein, a molding lens, and a filter. The molding lens comprises a solid cylindrical main body, and a pair of cylindrical protrusions respectively extending from opposite ends of the main body. The main body comprises an oblique end face, and an opposite aspherical end face. The ferrule is received in one protrusion and opposes the oblique end face. The filter is received in the other protrusion and opposes the aspherical end face.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompany drawings, in which: